Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$188.63	6.211%	$200.3458	$200.35	$200.35	$200.30
Purchase #2	$199.38	6.551%	$212.4414	$212.44	$212.45	$212.40
Purchase #3	$75.51	7.433%	$81.1227	$81.12	$81.10	$81.10
Purchase #4	$53.79	10.389%	$59.3782	$59.38	$59.40	$59.40
Purchase #5	$141.61	10.615%	$156.6419	$156.64	$156.65	$156.60
Purchase #6	$248.89	10.307%	$274.5431	$274.54	$274.55	$274.50
Purchase #7	$190.60	4.184%	$198.5747	$198.57	$198.55	$198.60
7 purchase totals =	$1,098.41		$1,183.0478	$1,183.04	$1,183.05	$1,182.90